Lu-Lu Xun

Hedysarum langranii sp. nov. (Fabaceae, Hedysareae) is described and illustrated from Shaanxi, Henan and Gansu, China. This new species is morphologically similar to H. smithianum , but can be distinguished by its glabrous stipules (vs. sparsely pubescent), standard petal 9–11 mm long (vs. 12–13 mm long), keel petals 12–13 mm long (vs. 14–15 mm long), androecium 13–15 mm long (vs. 16–17 mm long), loment articles 4–5 mm wide (vs. 5–7 mm wide). The new species can be easily distinguished from H. dentatoalatum by its papyraceous leaflets (vs. membranaceous), corolla pale purple or pink (vs. pale yellow); loment articles 5–7 × 4–5 mm, without prickle on the veins, with minute irregular teeth along both sutures (vs. 8–12 × 10–12 mm, with prickles on the veins, with wings and prominent teeth along both sutures). The phylogenetic tree based on the nuclear sequences shows that H. langranii is sister to H. dentatoalatum , while the tree based on the plastid sequences shows that H. langranii is sister to a clade consisting of H. smithianum and H. dentatoalatum. The new species and H. dentatoalatum are both diploids with a chromosome number 2 n = 14. Supplementary descriptions of H. smithianum and H. dentatoalatum are also provided. The incongruent phylogenetic position of H. dentatoalatum could be explained by an ancient hybridization hypothesis, but requires further investigation to determine the reason for this incongruence.

Piper bambusifolium Y.C. Tseng 1979, a climbing shrub of the family Piperaceae, has attracted increasing research attention due to its dual medicinal and ornamental value. This study presented the first complete chloroplast genome sequence of P. bambusifolium, spanning 161,476 bp with a GC content of 38.3%. The circular genome exhibited a typical quadripartite structure, consisting two inverted repeats (IRs; 27,058 bp each) that separate a large single-copy (LSC; 89,143 bp) and a small single-copy (SSC; 18,217 bp). The genome encoded 129 genes, including 83 protein-coding genes, 37 tRNA genes, and 8 rRNA genes. Phylogenetic analysis revealed the close relationship between P. bambusifolium and P. hencai within the family Piperaceae. Overall, our study expanded the genomic resources for P. bambusifolium, providing a valuable foundation for further exploration and utilization, and highlights the new insights into phylogenetic relationships within the family Piperaceae.

Astragalus zibaishanensis sp. nov. (Fabaceae) is described and illustrated from Shaanxi, China. This new species is similar to Astragalus monadelphus , A. xitaibaicus and A. neomonodelphus by having yellow petals, pseudomonadelphous androecium, and stipitate legumes, but can be distinguished by its stem 0.9–1.5 mm in diameter; leaflets 5–7, hairy adaxially and abaxially; calyx teeth triangular, ca. 0.5 mm long; standard 17–20 mm long; wings 18–21 mm long; keels 17–20 mm long; pistil glabrous; legume glabrous, with a stipe 10–11 mm long. Astragalus zibaishanensis is unique in Astragalus by having pseudomonadelphous androecium. Phylogenetic analyses confirm that the new species is a member of A. sect. Cenantrum. The nuclear ITS tree shows that A. zibaishanensis forms a clade with A. henryi , A. umbellatus , A. chilienshanensis , A. moellendorffii , A. przewalskii , A. monadelphus , A. xitaibaicus and A. neomonodelphus .

A new species, Orychophragmus yangiisp. nov., from the Loess Plateau of Shaanxi Province, China, is described and illustrated. This species differs clearly from all other Orychophragmus species in the following traits: whole plant glabrous; leaves varying from simple to pinnatifid but never lyrate; pinnatifid leaves with lobes divided or not; simple leaves widest at the base; sepals green; petals white; fruit narrowly linear, terete, and glabrous; rostra of fruit 2–4 mm long. Molecular phylogenetic analyses based on plastid genomic data and nuclear ribosomal RNA genes showed that the new species represents the first divergent lineage in the genus Orychophragmus. The chromosome number of the new species is 2n = 24.

Schisandra propinqua subsp. sinensis (Oliv.) R.M.K. Saunders 1997, a woody vine plant esteemed for its medicinal properties, has garnered attention in botanical research. In this study, we elucidated the complete chloroplast genome sequence of S. propinqua. The genome spans 145,562 bp and comprises a large single-copy (LSC) region of 94,164 bp, a small single-copy region of 18,294 bp (SSC), and a pair of inverted repeats (IR) of 16,552 bp. Notably, S. propinqua exhibits an overall GC content of 36.2%. Annotation revealed a total of 116 genes, encompassing 81 protein-coding genes, 27 transfer RNA (tRNA) genes, and 8 ribosomal RNA (rRNA) genes. Phylogenetic analysis unveiled a close relationship among Schisandraceae, indicating the evolutionary proximity. This comprehensive genomic dataset provides valuable insights into the genetic makeup and evolutionary dynamics within the Schisandra genus.

The genus Rorippa belongs to the family Brassicaceae, and its members usually have high medicinal value. The genus consists of approximately 75 species and mainly grows in the Northern Hemisphere, occurring in every continent except Antarctica. The taxonomy and phylogenetic relationships of Rorippa are still unsettled, largely due to complex morphological variations in Rorippa, which were caused by frequent hybridization events. Here, we sequenced four complete plastid genomes of Rorippa species by Illumina paired-end sequencing. The four new plastid genomes of Rorippa ranged in total size from 154,671 bp for R. palustris to 154,894 bp for R. sylvestris. There are 130 genes in the four plastomes, embodying 8 rRNA, 37 tRNA, and 85 protein-coding genes. Combining with six published plastid genomes, we carried on comparative and phylogenetic analyses. We found that the ten Rorippa plastid genomes were conservative in gene number and order, total size, genomic structure, codon usage, long repeat sequence, and SSR. Fourteen mutational hotspot regions could be selected as candidate DNA barcoding to distinguish Rorippa plants. The phylogenetic trees clearly identified that ten Rorippa species displayed monophyletic relationships within the tribe Cardamineae based on plastomes and nrDNA ITS sequences. However, there are significant cytonuclear discordances in the interspecific relationships within Rorippa, as well as the intergeneric relationships between Rorippa and its related genera. We inferred that the cytonuclear discordance is most likely a result of interspecific hybridization within Rorippa, as well as intergeneric hybridization with its related genera. These plastid genomes can offer precious information for studies of species authentication, evolutionary history, and the phylogeny of Rorippa.

The size of leaves is a vital factor in the development and overall biomass of a plant, serving as a key indicator of how a plant adapts to its environment. Rhamnus heterophylla, a species known for its heteromorphic leaves of varying sizes, presents an intriguing case for studying leaf development at the molecular level. To gain insights for further studies on the underlying mechanisms, we constructed a comprehensive reference transcriptome database using both SMART sequencing and Illumina RNA-seq technologies. Our analysis of the transcriptome data identified 88,546 isoforms, featuring an N50 size of 2386 base pairs. Furthermore, we identified 2932 transcription factors from 55 gene families, along with 14,947 unigenes that underwent alternative splicing. By comparing the gene expression patterns between large and small leaves, we pinpointed 982 differentially expressed genes (DEGs). Among these DEGs, 116 genes exhibit significantly greater activity in small leaves, while 866 genes display significantly greater activity in large leaves. Functional enrichment analyses revealed the significant involvement of these DEGs in various hormone signaling pathways. Notably, we detected a significant decrease in the expression of several genes associated with auxin synthesis, such as ARFs, GRF8, and IAA27, in small leaves. This finding sheds light on their potential role in leaf size regulation in R. heterophylla, providing valuable insights into the genes underlying this mechanism.

Hedysarum qilianshanense sp. nov. (Fabaceae, Hedysareae) is described and illustrated from the Qilianshan Mountains in Gansu, China. This new species is similar to H. przewalskii, but can be distinguished by its corolla being light purple to purple, standard 15–19 mm long, wings 14–16 mm long, keels 16–19 mm long, and the ovary and legume being glabrous. The new species can be easily distinguished from H. neglectum Ledeb. by its bract being shorter than the pedicel, and the ovary and legume being glabrous. Phylogenetic tree based on the nuclear ITS and ETS sequences shows that H. qilianshanense is sister to H. przewalskii, while the tree based on the plastid psbA-trnH, trnC-petN, trnL-F, trnS-G and petN-psbM sequences shows H. qilianshanense as sister to a clade consisting of H. hedysaroides, H. inundatum, H. americanum and H. neglectum. The new species is a diploid with the chromosome number 2n = 14. Based on morphological, phylogenetic and karyotypic evidence, the new species may originate from an ancient homoploid hybrid speciation event.

Plant glandular trichomes have received much attention due to their commercial and biological value. Recent studies have focused on the development of various glands in plants, suggesting that programmed cell death (PCD) may play an important role during the development of plant secretory structures. However, the development processes and cytological characteristics in different types of plant secretory structures differed significantly. This study aims to provide new data on the developmental PCD of the capitate glandular hairs in Dictamnus dasycarpus. Light, scanning, immunofluorescence labeling, and transmission electron microscopy were used to determine the different developmental processes of the capitate glandular hairs from a cytological perspective. Morphologically, the capitate glandular hair originates from one initial epidermal cell and differentiates into a multicellular trichome characterized by two basal cells, two lines of stalk cells, and a multicellular head. It is also histochemically detected by essential oils. TUNEL-positive reactions identified nuclei with diffused fluorescence or an irregular figure by DAPI, and Evans blue staining showed that the head and stalk cells lost their viability. Ultrastructural evidence revealed the developmental process by two possible modes of PCD. Non-autolytic PCD was characterized by buckling cell walls and degenerated nuclei, mitochondria, plastids, multivesicular body (MVB), and end-expanded endoplasmic reticulum in the condensed cytoplasm, which were mainly observed in the head cells. The MVB was detected in the degraded vacuole, a degraded nucleus with condensed chromatin and diffused membrane, and eventual loss of the vacuole membrane integrity exhibited typical evidence of vacuole-mediated autolytic PCD in the stalk cells. Furthermore, protoplasm degeneration coupled with dark oil droplets and numerous micro-dark osmiophilic substances was observed during late stages. The secretion mode of essential oils is also described in this paper.

In view of the traditional RC oscillator's low accuracy and inability to be adjusted, a new repairable and adjustable high-precision RC oscillator is proposed. The oscillator is composed of two inverters, comparators, controllable switches, capacitors and resistors. The comparator generates output voltage by comparing the capacitor voltage value and the reference voltage value. At the same time, it controls the working state of the switching MOS tube to complete the cyclic charge and discharge of the capacitor. The two groups of capacitors charge and discharge alternately, and then produce continuous oscillation waveform. The high-frequency clock is realized by alternating comparison between bilateral comparator and bias voltage. The advantage of this mode is that the oscillation frequency is only related to the charging time, but has nothing to do with the discharge time. There is no need to consider the influence of the discharge time delay on the frequency. In this paper, the coarse adjustment of the accuracy of the oscillator is realized by adjusting the charging current of the capacitor, and then the output of the oscillator is accurately adjusted by selecting the capacitance value of the capacitor.